Interview Questions to Ask Candidates: A Practical Guide
The best interview questions to ask candidates, organized by category, plus unique questions, follow-up probes, and what to avoid. A practical guide.
Interview Questions to Ask Candidates
What to ask, why it works, and how to get real answers
Early in my hiring career, I interviewed a candidate who gave perfect answers to every question I asked. Confident, articulate, well-prepared. I hired her. Within two months it was clear she could talk about the work far better than she could do it. The problem was not her; it was my questions. I had asked what she would do in various situations, and she had told me exactly what a good employee would say. I never once asked her to show me what she had actually done.
That hire taught me the single most important lesson about interviewing: the quality of your hire is capped by the quality of your questions. A great candidate answering weak questions looks the same as a mediocre candidate answering weak questions. The questions are what separate them. Yet most interviewers, especially at small companies without a formal hiring process, ask questions that sound reasonable but reveal almost nothing.
This guide gives you the interview questions that actually predict performance: the six categories worth covering, why behavioral questions beat hypotheticals, the best questions to ask in each category, unique questions that surface what standard ones miss, the follow-up probe that separates real answers from rehearsed ones, and the legal lines you cannot cross. I built FirstHR for the stretch from the signed offer letter through onboarding, and everything in that stretch runs more smoothly when the questions asked before the offer picked the right person.
Why the Right Interview Questions Matter
Interviewing is the highest-stakes, lowest-skill activity most managers perform. A hiring decision that goes wrong usually ends in a replacement, and Gallup puts the cost of replacing an individual employee at one-half to two times that employee's annual salary, which it calls a conservative estimate. Yet most interviewers have never been trained and rely on questions half-remembered from interviews they once sat through. The result feels rigorous but tells you little about who will do the job well.
The research on this is stark. According to the Office of Personnel Management's structured interview guide, research consistently indicates that unstructured interviews, the free-flowing conversation most managers default to, have little value in predicting job performance.
The same guide credits structured interviews with a high degree of reliability, validity, and legal defensibility. The gap between the two is not about the interviewer being smart or experienced. It comes down entirely to the questions and how consistently you ask them.
The 6 Categories of Interview Questions
A complete interview covers six categories of questions. You do not need many questions in each; you need at least one strong question per category, explored thoroughly. Covering all six means you judge the whole candidate, not just the part you personally find easiest to assess.
Most interviewers lean on one or two categories and neglect the rest. Technical managers focus on role and skills; people-oriented managers focus on collaboration and fit. The discipline is to cover all six deliberately, because the category you skip is usually the one where the eventual problem shows up.
Behavioral vs Hypothetical Questions
A hypothetical question asks what someone would do; a behavioral question asks what they actually did. This distinction, more than any other, separates effective interviewers from ineffective ones. The difference in signal is enormous.
| Dimension | Hypothetical Question | Behavioral Question |
|---|---|---|
| Form | "What would you do if a project was behind schedule?" | "Tell me about a time a project was behind schedule. What did you do?" |
| What it measures | How well the candidate knows the ideal answer | What the candidate actually did in a real situation |
| Rehearsability | High; candidates prepare polished ideal responses | Lower; real examples are harder to fabricate convincingly |
| Signal quality | Weak; describes aspiration, not behavior | Strong; past behavior predicts future behavior |
| Follow-up potential | Limited; the scenario is imaginary | High; you can probe specifics of the real situation |
| Best use | Testing scenarios the candidate genuinely has not faced | The default for nearly every competency you want to assess |
The practical rule: lead with behavioral questions for anything the candidate has plausibly encountered before, and reserve hypotheticals for genuinely novel scenarios you need to test.
When a candidate answers a behavioral question with a hypothetical ("well, I would usually..."), that is a signal in itself. Gently redirect them to a specific instance: "Can you give me an actual example of when that happened?" The candidates who cannot produce one often have not done the thing they are describing.
The main types of interview questions
Behavioral and hypothetical get the most attention, but an interviewer is really working with about seven question types. Most of the confusion in hiring advice comes from mixing up the format of a question with its subject, so the table below sorts them by what the question asks the candidate to produce.
| Type | What it asks for | Where it earns its place |
|---|---|---|
| Behavioral | A specific thing the candidate already did | The default for any competency they have plausibly used before |
| Situational | A judgment call in a scenario they have not yet faced | Genuinely new territory, and roles where handling the scenario is the job |
| Competency-based | Evidence against one defined competency, scored to a rubric | Comparing several candidates on the same dimension without drift |
| Technical or work sample | A small piece of the actual work, done live or as a short task | Verifying a skill claim that conversation alone cannot settle |
| Open-ended | A reasoned answer in the candidate's own framing | Almost everything, since a closed question caps the answer |
| Closed | A fact, a number, or a yes or no | Logistics only: notice period, certifications, work eligibility |
| Brainteaser | A puzzle with a trick answer | Nowhere useful. It mostly measures who has met the puzzle before |
Most interviews need only two of these: a behavioral core for what the person has already done, plus a situational question or a short work sample for the parts of the job they have not met yet. Competency framing is what turns either one into something you can score rather than something you merely remember.
The Best Interview Questions to Ask, by Category
Below are strong, reusable questions organized by the six categories. Adapt the wording to your specific role, but keep the behavioral framing. Ask the same core questions of every candidate so you can compare answers fairly.
| Category | Strong questions to ask |
|---|---|
| Role and skills | Walk me through a piece of work you did that is closest to what this role requires. Tell me about the most technically difficult problem you solved in your last job. What is a task in your current role you have gotten measurably better at, and how? |
| Problem-solving | Tell me about a time you had to solve a problem with incomplete information. Describe a situation where your first approach failed and you had to change course. When you hit a problem you have never seen before, what are your first three steps? |
| Collaboration and conflict | Tell me about a disagreement with a colleague and how it resolved. Describe a time you had to work with someone whose style was very different from yours. When have you had to give someone difficult feedback? |
| Motivation and fit | Why this role, at this company, right now? What would make you leave a job you otherwise liked? What kind of work makes you lose track of time? |
| Communication | Explain your current job to me as if I have never worked in your field. Tell me about a time you had to explain something complex to a non-expert. Describe a time a message you sent was misunderstood and what you learned. |
| Self-awareness and growth | Tell me about a decision you got wrong and what changed afterward. What is a piece of feedback that was hard to hear but correct? What are you actively trying to get better at right now? |
These questions work across almost any role because they target transferable signals rather than role-specific trivia.
Strategic interview questions: chosen for signal, not for variety
A strategic interview question is not a separate species of question. It is any question picked because it maps to something the role genuinely has to deliver, then asked of every candidate so the answers can be set side by side. The opposite is a list of interesting questions assembled the night before.
Three strategic questions work in almost any role, because every job involves choosing what not to do: "Tell me about a time you had to choose between two things that both mattered, and how you decided." "What did you stop doing in your last job, and who was unhappy about it?" "What is something your last employer got wrong that you would have pushed to change?"
Build the rest of the set from the role rather than from a list. Write down the three outcomes this hire owns in their first year, then write one question per outcome asking for evidence they have produced something similar before. A short set built that way outperforms a dozen general questions asked in a different order every time.
Unique Interview Questions to Ask Candidates
Standard questions have one weakness: candidates prepare for them. Anyone who has read a few interview-prep articles arrives with polished answers to "what is your greatest weakness?" and "tell me about a conflict." Unique questions solve this by asking something the candidate has not rehearsed, which forces genuine, in-the-moment thinking.
The catch is that a unique question is only useful if it still maps to a real, job-relevant signal. A question that is merely quirky is entertainment; a question that is unexpected and reveals how someone reasons, what they value, or how clearly they communicate is a tool.
The four groups below organize unique questions by what they actually reveal. Use one or two per interview, not a barrage; the goal is to catch the candidate slightly off-script, not to interrogate them with curveballs. Pair each with a genuine follow-up so the unique question opens a real conversation rather than producing a one-line performance.
Notice what none of these questions are: brainteasers. Riddle-style puzzles ("how many ping-pong balls fit in a car?") were popularized by large tech companies and have since largely fallen out of favor.
A 2022 SHRM viewpoint on interview questions, written by two business school professors, puts brainteasers among the questions that have no proven track record of predicting who will best perform the job.
A good unique question passes a two-part test. It is unexpected but answerable from the candidate's own experience and thinking, and you can name the signal it checks: reasoning under pressure, honest self-reflection, genuine values, or clarity of communication. If you cannot name what a question reveals, do not ask it.
Casual interview questions and what they are actually for
Casual questions do one job: they get a nervous person talking in their own voice before the evaluation starts. The first five minutes decide how much an interviewee will tell you across the next forty, and a candidate still braced for a test hands you rehearsed answers to everything that follows.
Good openers stay on the work while sounding like conversation: "What part of your current job would you happily do all day?" "How did you end up in this field?" "What made you open our posting?" Each is answerable with no preparation, tells you something real about motivation, and costs about a minute.
The risk is that casual is exactly where off-limits questions slip out. Weekend plans, family, where somebody grew up, and which holidays they keep all feel like small talk and all touch protected ground. Keep the warm-up on their working life, and put the friendliness in your tone rather than in the subject.
The Follow-Up Probe That Surfaces the Truth
The most valuable part of an interview is rarely the initial answer. It is the follow-up. A prepared candidate has a polished response ready for the first question; almost nobody prepares for the third layer of follow-up. That is where the real signal lives, and where most interviewers stop too early.
The technique is simple: after any answer, keep going deeper on the specifics. If a candidate says they "led a project that improved results," the follow-ups are "What specifically was your role versus the team's?" "What was the single hardest decision you made?" "What would you do differently?" and "Who disagreed with your approach, and what happened?"
Each layer of follow-up strips away the rehearsed surface and gets closer to what actually happened. Candidates describing real experience can go three or four layers deep with specifics; candidates describing borrowed or exaggerated experience run out of detail quickly.
| Layer | Question type | What it surfaces |
|---|---|---|
| Layer 1 | The initial question ("tell me about a project you led") | The candidate's prepared, high-level narrative |
| Layer 2 | Specifics ("what exactly was your role?") | Whether they actually did the work or were adjacent to it |
| Layer 3 | Difficulty ("what was the hardest decision?") | Judgment, ownership, and how they handle real trade-offs |
| Layer 4 | Reflection ("what would you do differently?") | Self-awareness and capacity to learn from experience |
The discipline that makes follow-ups work is silence. After you ask a probing question, stop talking and let the candidate think, even through an uncomfortable pause. Interviewers who rush to fill silence rob themselves of the most revealing answers.
The layer where a candidate runs out of detail is hard to notice in the room and obvious on paper, so run the probe against a sheet: one claim per page, what they said at each layer, and a mark for whether the answer was still specific.
Interview Questions You Cannot Legally Ask
Some questions are illegal regardless of how well-intentioned they are. The Equal Employment Opportunity Commission (EEOC) holds that what you ask an applicant should be limited to what is essential for deciding whether the person is qualified, and that race, sex, national origin, age, and religion are irrelevant to that decision.
That standard covers indirect questions as fully as direct ones. An interviewer who asks "when did you graduate?" out of friendly curiosity has still asked a question that reveals age, which the Age Discrimination in Employment Act (ADEA) protects from 40 onward.
The EEOC makes the same point about asking which clubs, societies, and lodges someone belongs to, because the answer can indicate race, national origin, or religion without the question ever naming them.
| Area of risk | Do not ask (directly or indirectly) | Ask instead |
|---|---|---|
| Age | When did you graduate? How old are you? | Are you over the minimum age this role requires? |
| National origin | Where are you from originally? What is your first language? | Are you authorized to work in the US? |
| Family status | Do you have children? Are you planning a family? | Are you able to meet the schedule this role requires? |
| Religion | What church do you attend? What holidays do you observe? | Are you available to work the shifts this role requires? |
| Disability | Do you have any health conditions? Have you filed a workers' comp claim? | Can you perform the essential functions of this role, with or without accommodation? |
| Arrest record | Have you ever been arrested? | Follow applicable ban-the-box and background-check law for your jurisdiction |
Two rows on that table need a footnote. The first is family status. Caregiver status is not itself a federal protected characteristic: the EEOC caregiver guidance says the federal equal employment opportunity laws do not prohibit discrimination against caregivers as such.
The same EEOC guidance does treat one pattern as evidence of sex discrimination under Title VII of the Civil Rights Act: asking female applicants, and not male ones, whether they are married or have young children.
The second is the arrest record row. Arrest and conviction history is not a protected characteristic either, and what you may ask about it is set by state and city ban-the-box law (rules that limit when an employer may ask about criminal history) rather than by one federal rule.
The safe principle is simple: every question should connect to the candidate's ability to do the job. If a question is about who the person is rather than what they can do, it is either illegal or a step toward it.
The same principle applies with equal force to unique and creative questions, which can wander into protected territory precisely because they are unscripted. This article is general guidance, not legal advice; consult an employment attorney for your specific situation.
Common Interviewing Mistakes
Nearly every untrained interviewer makes the same five mistakes. All of them are fixable, and fixing them improves hiring quality more than any amount of interviewer charisma.
The pattern across all five: interviewing well is a discipline, not a personality trait. The interviewers who reliably make good hires are not the most charming or the most experienced; they are the ones who ask consistent behavioral questions, probe past the first answer, listen more than they talk, and stay on the right side of the legal line.
You can start with your next opening. Pick one behavioral question per category, plan the follow-ups you will use to probe each answer, and ask that same set of every candidate for the role.
Frequently Asked Questions
What are the best interview questions to ask candidates?
The best interview questions are behavioral and specific: they ask candidates to describe real past situations rather than hypotheticals. Strong examples include 'Tell me about a time you had to solve a problem with limited resources,' 'Describe a disagreement with a colleague and how it resolved,' and 'Walk me through a decision you got wrong and what changed afterward.' The most reliable questions target the exact skills the role requires and ask for concrete examples, because past behavior on the same task is the best available predictor of future behavior. Combine role-specific questions with a few that test problem-solving, collaboration, and self-awareness.
What are good unique interview questions to ask candidates?
Good unique interview questions are ones a candidate has no way to prepare for, so the answer shows how they think on the spot while still telling you something about the job. Four that work well: 'If you could change one thing about how our industry operates, what would it be?', 'What is one negative word a former colleague might use to describe you, and is it fair?', 'Teach me something you understand well in two minutes,' and 'If you started a company tomorrow, what are the first three rules you would set for how people work together?' Each one earns its place by testing something specific (reasoning, self-awareness, values, or communication); a question that tests nothing is a gimmick. Skip pure trivia and riddle-style brainteasers, which a 2022 viewpoint published by SHRM lists among the questions that have never been shown to predict who will do the job best. Creative questions also have to stay away from protected characteristics such as age, religion, or disability. Federal law bars pre-offer disability questions outright, and probing the others can become evidence of discrimination no matter how the question is worded.
What is the difference between behavioral and hypothetical interview questions?
Behavioral questions ask about real past situations ('Tell me about a time you missed a deadline'), while hypothetical questions ask about imagined future scenarios ('What would you do if you missed a deadline?'). Behavioral questions are more reliable because they surface actual past behavior, which predicts future behavior better than a candidate's idealized description of what they think they would do. Hypotheticals invite rehearsed, aspirational answers. The strongest interviews lead with behavioral questions and use hypotheticals only to test scenarios the candidate genuinely has not encountered.
How many questions should you ask in an interview?
For a typical 45-60 minute interview, plan for 6-10 core questions with room for follow-up probes on each. Depth matters more than breadth: a single behavioral question explored thoroughly through follow-ups reveals more than five surface-level questions rushed through. Leave the final 10 minutes for the candidate's own questions, which are themselves a signal. The goal is a structured set of core questions asked of every candidate for fair comparison, plus the flexibility to probe deeper where a specific answer warrants it.
What questions are illegal to ask in an interview?
Federal law flatly bars two kinds: pre-offer questions about disability, and requests for genetic information. Questions that reveal age, race, color, religion, national origin, sex, or pregnancy are not banned outright by federal statute, but the EEOC says they should generally be avoided, because the answers can be used as evidence of discrimination unless a business purpose justifies asking. Indirect versions carry the same risk: 'When did you graduate?' points to age, 'Where are you from originally?' to national origin, 'Do you have children?' to sex stereotyping, and 'What church do you attend?' to religion. Caregiving works differently. Federal law does not protect it as a characteristic in its own right, but EEOC guidance treats a question about young children put only to female applicants as evidence of sex discrimination under Title VII. Good intentions do not remove the risk, and creative or unusual questions are as exposed to it as standard ones. The safest habit is to ask only about the work and whether the candidate can do it, never about personal traits that have nothing to do with the job.
Should you ask every candidate the same interview questions?
Yes, for the core questions. Putting the same core questions to every candidate, in the same order, and scoring the answers against the same evaluation criteria is known as a structured interview. The Office of Personnel Management's guide rates that format high on reliability, validity, and legal defensibility, and the research behind it finds free-form, unstructured conversation of little use for forecasting job performance. Identical core questions are what make a fair side-by-side comparison possible, and they shrink the room unconscious bias gets when each interview drifts somewhere different. Follow-up probes can still vary from one candidate to the next: the structure governs the core question set, not every word you say.
Do brainteaser interview questions work?
Generally no. Riddle-style brainteasers ('How many golf balls fit in a school bus?') owe their fame to large tech companies, and the practice has largely faded since. Two business school professors, writing in a 2022 SHRM viewpoint, list them among the question types with nothing to show that they predict job performance. In practice, a brainteaser mainly tests whether the candidate has heard that riddle before, and the pressure it creates tends to hide genuine ability rather than reveal it. Creative questions are a different matter: they are worth asking when each one points at something the job needs, such as reasoning, communication, or values, instead of at a trick answer. If you cannot connect a question to a real requirement of the role, it is entertainment, not evaluation.